1. Field of the Invention
The present invention relates to a sheet feeding device and an image forming apparatus.
2. Description of the Related Art
In recent years, the printing market has increasing needs for a printout on elongated sheets, such as coated sheets, in the fields of book covers, facing pages of catalogs, POP advertising, or the like, and there is also demand for a printout on elongated sheets and an increase in the number of loaded elongated sheets in the PP business field. Here, POP is an abbreviation for Point of purchase advertising, and PP is an abbreviation for Production Printer.
For a printout on elongated sheets by using copiers, it is difficult to supply the sheets to a commonly used sheet feeding tray, as the length of the elongated sheets is different from the length of regular sheets; therefore, there is an already-known technology for gradually supplying sheets for printing by using a manual feed tray, or the like, that is installed in a copier.
However, it is difficult to load a large quantity of elongated sheets by using conventional manual feed trays of copiers. Furthermore, even if they are loaded, they cannot be stored in a stable state as the manual feed tray causes the sheets to be exposed on the outside of a chassis; therefore, there is a need to previously take, from a pack of sheets, the sheets enough for printing and supply them for printing, which results in the problem of a decrease in the printing operation efficiency.
Furthermore, there is a problem in that, during a supply of elongated sheets, it is difficult to place the sheets even by using a manual feed tray due to the characteristics of the sheets, i.e., the weight of loaded sheets is heavy, or elongated sheets are bent more than regular sheets when they are lifted up because the elongated sheets are longer than the regular sheets. Furthermore, there is a problem in that, if a sheet feeding tray, such as a commonly used large-capacity sheet feeding tray unit (hereinafter, referred to as the “LCT”), is designed for elongated sheets, the size of the sheet feeding tray is increased and the size of the overall sheet feeding device is increased, which results in an increase in the installation space for the sheet feeding device.
The technology that is described in Japanese Patent Application Laid-open No. 06-092486 is intended to allow a supply of sheets in a high position and improve the operability. Japanese Patent Application Laid-open No. 06-092486 discloses the configuration of a sheet feeding device that includes a sheet container that is made up of a box-shaped open-topped frame member and that can be pulled out toward the front side of a main body on rails; a bottom plate that is located inside the sheet container and that moves vertically with a large quantity of sheets loaded thereon; a bottom-plate drive unit that lifts and lowers the bottom plate; and a sheet feeding unit that feeds the loaded sheets from the upper side, wherein the sheet feeding device includes a small tray that is located in the upper section of the sheet container to supply the sheets onto the bottom plate and includes a guide unit for pulling out the small tray toward the front side.
However, the technology that is described in Japanese Patent Application Laid-open No. 06-092486 does not resolve the problem of an increase in the installation space for the sheet feeding device because the size of the sheet feeding tray is increased if the tray is designed for elongated sheets.
Therefore, it is desirable to provide a sheet feeding device that can store elongated sheets in a stable manner and that can supply sheets with high-accuracy positioning without making major changes on the structure of the existing tray.